<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="./jquery-3.7.1.min.js"></script>
</head>
<body>
    <table border="1">
        <tr>
            <td>Row with Index #0</td>
        </tr>

        <tr>
            <td>Row with Index #1</td>
        </tr>

        <tr>
            <td>Row with Index #2</td>
        </tr>

        <tr>
            <td>Row with Index #3</td> 
        </tr>

        <script>
            //jQuery扩展选择器,even偶数选择器 注意，从0开始

            $("tr:even").css("background-color","red")
        </script>
    </table>
</body>
</html>